GLOSSARY
Every metric on Read The Game, defined in plain language. Each entry is linkable —
append the anchor (e.g. #impact) to deep-link a definition.
For the full math, see the methodology page.
The Headline Metric
Impact
The primary player-evaluation number on Read The Game, expressed in points per game above or below league average (zero-centered). Impact blends two independent signals: a per-game box-score possession value — which values every event (shot, assist, rebound, turnover, foul, hustle play) by the possession value it creates relative to expectation, with shots difficulty-adjusted against a 1,030,404-shot training set — and a season-level RAPM (Regularized Adjusted Plus-Minus), team-demeaned to remove squad-quality effects. The two are combined by per-player inverse-variance weights, so the blend automatically leans on whichever signal is more reliable for that player — no global tuning knob. The median player is roughly 60% box-score, 40% RAPM. Full derivation on the methodology page; out-of-sample accuracy is published on the validation page.
PBP Credit & Components
PBP Credit
A play-by-play decomposition of the box-score signal — same shot-difficulty framework, but computed event-by-event from the raw play-by-play stream. It is a diagnostic view, not the Impact number itself: the six component columns below answer questions like "is this player's value coming from scoring or creation?" A player's total PBP Credit closely tracks their box-score impact, but resolves details the box score can't (live-ball vs dead-ball turnovers, assist-to-layup vs assist-to-three).
Scoring
Points scored plus difficulty-adjusted miss penalties. A made shot earns the points plus a bonus scaled by how hard the shot was; a missed shot is penalized by the value an average player would have produced from the same attempt. Tough shot-makers aren't punished like players bricking open looks.
Creation
The value of shots created for teammates. When a player's pass leads directly to a shot, the creator is credited with the expected value of that shot (based on its type and difficulty) minus the cost of the possession used. Setting up a teammate's open corner three is worth more than a contested long two — regardless of whether the shot goes in.
Shot-Making
The bonus for making shots above expected FG%. Every shot is classified into one of 121 types by subtype, distance, and value (2pt/3pt), each with a league-wide expected make rate trained on over a million NBA shots. Beating that expectation earns shot-making credit; the metric isolates pure finishing skill from shot selection.
Defense
Credit from defensive events captured in the play-by-play: steals, blocks, charges drawn, and fouls. Each event is valued by the possession value it adds or removes. Note that play-by-play only sees recorded events — off-ball defense is better captured by the tracking-based Leverage (defense) column.
Hustle
Offensive and defensive rebounds, plus blocks. Each rebound is valued by the possession it secures or extends — an offensive board that gives the team another shot is worth more than a routine defensive board everyone expected.
Turnover Value
The cost of turnovers, signed negative. Live-ball turnovers (steals leading to transition the other way) cost −2.37 points of possession value; dead-ball turnovers (stepping out, offensive fouls) cost −1.12, since the defense must set up again. Ball-handlers with careless live-ball giveaways are penalized more than players with occasional dead-ball miscues.
NBA Tracking Metrics
Gravity
Defensive attention drawn above expected — how much help-defense a player's on-ball or off-ball position forces the defense to commit, from the NBA's optical-tracking feed. A shooter who bends the defense just by standing in the corner registers gravity even without touching the ball. Shown alongside Impact as an independent third lens on the same player.
Leverage
Win-probability-weighted impact: events in high-leverage game states count more than garbage time. A go-ahead bucket with a minute left moves the number far more than the same bucket up twenty. Split into creation (shot-creation actions) and defense (defensive actions) shares — the defense share is especially valuable because tracking sees off-ball defense that play-by-play misses.
Shot Quality (xFG)
The average expected value of the shots a player takes, before accounting for whether they go in. Expected FG% (xFG) comes from the league-wide make rate for each shot type — so a diet of rim attempts and open threes scores high, contested long twos score low. On the leaderboard, FG% minus xFG shows shot-making: actual conversion above or below what the shot diet predicts.
Team & Lineup
On/Off Swing
The team's net rating (points per 100 possessions) with a player on the floor minus its net rating with them off. A +8 swing means the team is eight points per 100 better when they play. Powerful but noisy in small samples — who you share the floor with matters — which is why Impact uses the regression-based RAPM rather than raw on/off.
Lineup Net Rating
Offensive rating minus defensive rating for a specific five-man unit, per 100 possessions. Team pages show the best lineups with a minimum of 100 possessions on each end, so a hot twenty-possession stretch doesn't masquerade as a great lineup.
Net Rating (NetRtg / OffRtg / DefRtg)
Offensive rating is points scored per 100 possessions; defensive rating is points allowed per 100; net rating is the difference. Per-100 framing strips out pace, so fast and slow teams are directly comparable. Applied to a player, it reflects the team's per-100 numbers during their minutes.
Efficiency & Usage
eFG% (Effective Field Goal Percentage)
Field goal percentage with three-pointers counted as 1.5 makes, since a three is worth 50% more than a two. A player shooting 40% on threes is as efficient as one shooting 60% on twos, and eFG% reflects that where raw FG% does not.
TS% (True Shooting Percentage)
The most complete scoring-efficiency stat: points per scoring attempt, counting free throws as well as twos and threes. A player who lives at the line can have a modest FG% but an elite TS%. League average sits in the high 50s.
TOV% (Turnover Percentage)
The share of possessions used that end in a turnover. Unlike raw turnover counts, it is rate-based — a high-usage creator with 4 turnovers in 80 possessions is taking better care of the ball than a low-usage player with 3 in 30. Lower is better.
FT Rate (Free Throw Rate)
Free throw attempts relative to field goal attempts — how often a player or team gets to the line per shot taken. Drawing fouls produces the most efficient points in basketball, so a high FT rate is a hallmark of efficient offenses and downhill scorers.
Usage (USG%)
The share of team possessions a player finishes while on the floor — with a shot, free throws, or a turnover. Stars typically run 28–35%; role players 12–18%. Context for every efficiency stat: maintaining elite efficiency at high usage is far harder than at low usage.
Want the equations behind these numbers? Read the full methodology and the nightly-recomputed validation numbers.